The  UnitIed  States  Deedg-ihg 


AND  COH^TEIJCTIOH  COMPANY 


Digitized  by  the  Internet  Archive 
in  2019  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/unitedstatesdredOOunse 


INDEX  TO  CONTENTS. 


Pages  5  to  12  — Financial  Scheme. 

Purchase  price  of  Patents. 
Capital  of  Company. 

Issne  of  Shares. 

Bonus,- 

Page  9  - Patents  to  be  purchased. 

“  11  — Form  OE  Subscription. 


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J3 _ Evolution  of  the  Fruhling  system. 

11  ....  The  German  Government  and  the  Fruhling  System  op  Dredging, 

11  _ Advantages  of  the  Fruhling  System  of  Dredging. 

15-16  _ Dredging  in  the  United  States  op  America. 

The  Panama  Canal. 

The  Erie  Canal. 

The  Mississippi  River  Commission. 

New  York  Harbor  and  the  Ambrose  Channel. 

18-20  - Prices  Paid  for  Dredging  Work. 

18  . . .  .Various  large  dredging  works  in  America. 

20-22  ....  Policy  of  the  Company. 


Page  25  . . .  .Certificate  Relating  to  the  Merits  op  the  Fruhling  System  op 

Dredging  by  Herr  Scholer  (Chief  Engineer  to  the  German  Gov¬ 
ernment  River  and  Harbors  Department,  Member  Imperial  Canal 
Commission  of  Kiel,  Germany,  &c). 

Pages  27-32  ....Report  on  the  Fruhling  system  of  Dredging,  by  Messrs.  Flannery 

Baggallay  &  Johnson,  of  London,  England. 

“  33-40  _ Report  on  the  Fruhling  system  of  Dredging,  by  Herr  Scholer. 


9 


UNITED  STATES  PATENT  RIGHTS  TO  BE  PURCHASED  BY  THE  COMPANY. 


No,  708,541  of  1902.  Improved  method  of  emptying  dredging  boats. 
No.  776,049  of  1904.  Improved  dredging  apparatus. 

No.  776,050  of  1904,  Improved  dredging  apparatus. 

No.  776,051  of  1904.  Improved  dredging  apparatus. 


By  the  purchase  of  the  patented  inventions  described,  the  United  States  Dredg¬ 
ing  AND  Construction  Company  would  also  acquire  the  sole  and  entire  right  to  purchase 
all  or  any  alterations  or  improvements  that  are  being  or  may  be  made  by  the  inventor 
at  any  time  thereon,  and  in  addition  the  sole  and  entire  right  to  take  out  in  the  United 
States  Patent  Bights  for  such  improvements  and  alterations  in  all  or  any  of  the 
patents  hereinbefore  described,  all  Patent  Bights  so  taken  out  becoming  the  absolute 
property  of  the  Company,  in  addition  to  the  Patent  Bights  more  particularly  men¬ 
tioned  hereinbefore. 


13 


LACK  OF  IMPROVEMENT  IN  DREDGING  APPARATUS. 

Mechanical  genius  has  not  applied  itself  to  the  improvement  of  dredging  apparatus, 
but  has  turned  to  more  popular  branches  of  engineering.  Consequently  dredging  has 
been  carried  on  with  machines  of  the  same  type  as  were  in  use  fifty  years  ago,  on  a 
scale  which  was  then  unthought  of.  These  machines  raise  all  the  various  materials 
in  which  dredging  operations  are  conducted,  and  fifty  years  ago  were  capable  of 
dredging  ports  and  harbors  quickly  enough  to  cope  with  the  amount  of  work  necessary. 

INCREASED  SIZE  OP  VESSELS  AND  URGENT  NEED  OF  DREDGING. 

Within  a  few  years,  however,  both  cargo  and  passenger  vessels  have  increased  in 
size  and  draft  to  such  an  extent  that  few  ports  and  harbors  can  accommodate  the  largest 
of  them.  Inability  to  accommodate  these  vessels  means  commercial  extinction,  and 
consequently  ports  all  over  the  world  are  faced  with  dredging  problems  of  great  magnitude. 
Where  a  few  years  ago  the  removal  of  a  few  thousand  cubic  yards  was  all  that  was 
necessary,  millions  of  cubic  yards  must  now  be  dealt  with.  No  port  had  time  to  accom¬ 
plish  a  gradual  increase  of  its  accommodation  facilities,  and  the  immediate  need  of 
machines  capable  of  removing  materials  with  a  speed  which  no  adaptation  of  existing 
types  could  accomplish  became  apparent. 

EVOLUTION  OP  THE  PRUHLING  SYSTEM. 

The  Suez  Canal  and  Bazine’s  Suction  Dredger — Sand. 

When  the  Suez  Canal  was  commenced  it  was  soon  found  that  machines  then 
known  could  not  deal  efficiently  with  the  vast  quantities  of  sand  of  which  the  major 
portion  of  the  work  consisted.  The  difficulty  was  overcome  by  Monsieur  Bazine  with 
the  Suction  Dredger.  This  invention  proved  entirely  successful  in  dealing  with  the 
material  in  which  it  was  designed  to  work.  At  that  time  the  chief  dredging  problem 
was  the  removal  of  sand-bars,  and  it  was  thought  that  with  the  suction  dredger  to  deal 
with  sand  and  the  bucket  dredger  and  grab  or  clam-shell  dredger  to  deal  with  mud  and 
clay  and  other  heavier  substances,  dredging  machinery  was  ready  to  deal  with  every 
description  of  work.  Bazine,  however,  attempted  to  dredge  mud  with  his  machine 
and  failed  completely.  Mud  being  then  not  a  very  great  factor  in  dredging,  slight 
importance  was  attached  to  the  suction  dredger’s  failure  when  such  work  was  attempted. 

When,  however,  the  extent  of  dredging  operations  necessary  was  so  suddenly 
increased,  new  problems  faced  the  engineers.  The  suction  dredger  was  again  put  to 
work  in  mud,  and  again  failed.  The  reason  for  the  failure  is:  Sand  is  a  very  heavy 
substance,  which,  when  sucked  up  by  the  suction  pipe  of  the  dredger  and  emptied  into 
barges  or  the  dredger’s  owm  hold,  falls  very  qnickly  to  the  bottom  of  the  barge  or  hold, 
and,  moreover,  does  not  require  the  admixture  of  a  very  large  percentage  of  water  to  be 
sucked  up  with  it.  Mud,  on  the  other  hand,  requires  to  be  mixed  with  a  large  percentage 
of  water  before  the  suction  will  draw  it  up  the  pipe,  and,  when  emptied  into  the 
barge  or  hold,  remains  in  suspension  and  does. not  sink  to  the  bottom.  The  percentage 
of  solids  to  water  varies  to  a  very  great  degree,  but,  it  will  be  seen  that,  if  yO  per  cent,  of 
water  has  to  be  drawn  up  with  10  per  cent,  of  mud,  only  10  per  cent,  of  the  power  of  the 
vessel  is  being  effective  in  actual  dredging,  and  the  waste  of  power  is  obviously 
enormous. 


14 


THE  KIEL  CANAL  AND  THE  FRUHLINC  SYSTEM  OF  DREDGING  BY 

SUCTION.— MUD. 

The  urgent  need  of  a  machine  to  dredge  the  sand  in  the  Suez  Canal  introduced 
Bazine  and  his  suction  dredger.  The  problem  of  dredging  the  mud  and  maintaining 
the  entrances  to  the  Kiel  Canal  gave  rise  to  the  invention  of  the  Fruhling  System  of 
Dredging  by  Herr  Otto  Fruhling,  of  Brunswick  in  Germany.  This  invention  enabled 
the  suction  system  to  be  applied  to  the  dredging  of  materials,  which  could  only  be 
accomplished  previously  by  means  of  the  bucket  and  clam  or  grab  dredgers. 

The  Fruhling  System  resulted  in  the  dredging  of  the  heavier  materials  with 
enormous  increase  in  speed  and  decrease  in  cost,  and  moreover  gave  to  the  engineers  a 
tool  which  could  also  be  worked  with  even  greater  speed  and  economy  in  sand.  In  one 
dredger  therefore  is  combined  an  implement  which  is  a  very  considerable  improvement 
in  sand  dredgers  and  an  incalculable  improvement  in  mud  dredgers. 

THE  GERMAN  GOVERNMENT  AND  THE  FRUHLING  SYSTEM. 

The  Fruhling  system  of  dredging  would  not  be  acquired  when  in  its  experimental 
stage  by  the  Company.  Since  1902  the  German  Government  has  expended  from  $500,000 
to  $750,000  on  the  construction  of  these  machines,  has  adopted  the  system  throughout 
the  empire,  and  has  now  under  construction  further  machines  to  cost  nearly  twice  the 
amount  already  expended  during  the  last  three  years.  Fruhling  dredges  are  now  being 
built  for  employment  in  nearly  all  the  German  ports  of  importance  on  the  Baltic  Sea. 

In  addition,  the  British  Dredging  Company,  Ltd.,  has  already  constructed  two  of 
these  vessels  and  has  further  vessels  under  construction,  and  lately  despatched  a  dredger 
under  her  own  steam  from  Holland  to  Shanghai.  The  vessel  arrived  at  her  destination 
without  having  experienced  the  slightest  mishap.  This  quality  of  seaworthiness  is  one 
of  the  notable  advantages  of  the  type.  No  insurance  premium  above  the  ordinary 
marine  rate  for  cargo  vessels  was  paid  on  the  vessel  for  the  voyage,  thus  demonstrating 
the  high  idea  of  her  qualities  held  by  insurance  firms.  Seaworthiness  is  of  no  small 
importance  when  the  necessity  for  long  and  rough  voyages  and  work  in  rough  waters  is 
considered. 

The  Inventor,  Herr  Otto  Fruhling,  one  of  the  greatest  experts  in  dredging  of  the 
present  time,  has  been  retained  as  consulting  engineer  by  the  Company. 

ADVANTAGES  OF  THE  FRUHLING  SYSTEM  OF  SUCTION  DREDGING  OVER 

OTHER  SYSTEMS  OF  SUCTION  DREDGING. 

The  numerous  separate  advantages  ensuing  from  the  use  of  the  Fruhling  system 
OF  DREDGING  are  explained  in  detail  and  in  technical  language  by  experts  in  the  accom¬ 
panying  reports.  Its  main  advantages  may,  however,  be  tabulated  as  follows: 

It  is  the  only  means  whereby  the  suction  system  of  dredging  may  be  equally 
successfully  applied  to  work  in  mud  and  sand. 

It  reduces  the  cost  of  working  by  75  per  cent. 

It  is  the  only  system  which  ensures  the  dredging  of  a  level  bottom. 

It  is  capable  of  working  in  a  sea-way  when  it  is  impossible  for  other  dredgers 
to  be  employed. 


16 


It  can  be  employed  in  work  in  narrow  and  confined  spaces  such  as  canals, 
docks  and  wharfs  without  fear  of  undermining  the  foundations  of  such 
structures  by  the  dredging  of  holes  in  proximity  thereto. 

It  has  been  proved  by  years  of  exhaustive  and  complete  trials  undertaken 
with  characteristic  thoroughness  by  the  German  Government  to  possess 
all  of  the  advantages  mentioned  above.  Information  regarding  the  sys¬ 
tem  may  be  obtained  by  application  to  the  German  Government  Harbor 
authorities  in  Germany. 

VARIOUS  MATERIALS  MET  WITH  IN  DREDGING. 

The  various  grades  of  materials  met  with  in  dredging  operations  may  be  briefly 
enumerated  as  follows; 

Sand,  silt  or  sand  and  mud  mixed,  clayey  mud,  gravel  (sand  and  stones  mixed 
together);  clay;  “hard-pan,”  a  material  consisting  of  a  peculiar  kind  of  clay  mixed  with 
stones  of  larger  size  than  those  usually  described  as  gravel,  which  hardens  into  a  very 
hard  cement-like  substance;  boulders,  and  bed  or  slab-rock. 

Of  these  materials  the  Fruhling  System  can  deal  with  all  excepting  clay,  hard- 
pan,  boulders,  bed  or  slab  rock,  it  is  possible  to  deal  with  gravel,  but  it  is  not  often 
attempted  on  account  of  its  being  apt  to  “score”  or  wear  out  the  inner  casing  of  the 
suction  pipes. 


SOME  INSTANCES  OF  DREDGING  AND  EXCAVATION  WORK  IN  THE  UNITED 

STATES. 

THE  PANAMA  CANAL. 

Though  the  need  for  dredging  the  actual  canal  has  not  yet  arrived,  important 
maintenance  dredging  work  must  be  at  once  proceeded  with  at  the  ports  of  Colon 
and  Panama  so  that  ocean-going  vessels  bringing  supplies  for  the  canal  work  may 
enter  and  leave  in  safety.  The  material  met  with  in  dredging  work  in  these  localities 
is  MUD,  and  therefore  peculiarly  suitable  to  the  Fruhling  system. 

As  water  is  admitted  to  the  completed  portions  of  the  Canal  the  amount  of 
dredging  work  will  of  course  increase,  and  as  the  Fruhling  system  is  especially  adapted 
to  work  in  narrow  spaces,  dredges  a  perfectly  level  bottom,  and  deals  with  such  a  wide 
range  of  materials,  it  should  be  very  largely  employed  in  the  dredging  of  the  Canal. 
The  great  reduction  of  the  expense  of  dredging  work  attained  by  use  of  the  Fruhling 
system  must  also  be  an  argument  greatly  in  its  favor. 

The  authorities  who  will  superintend  the  construction,  excavation  and  up-keep  of 
the  Canal  must  employ  the  best  tools  to  accomplish  the  end  in  view,  and  it  has  been 
proved  beyond  any  possibility  of  doubt  by  the  German  Government  engineers,  who  are 
famous  perhaps  above  all  others  for  thoroughness  and  conservatism,  that  the  Fruhling 
system  is  the  best  dredging  tool  extant  for  work  in  sand  and  mud. 

Of  the  $200,000,000,  or  whatever  the  eventual  sum  may  be,  which  is  expended  on 
the  Panama  Canal  works,  a  very  large  portion  must  be  expended  in  dredging  work  in 
material  in  which  the  Fruhling  system  has  won  its  chief  successes. 


16 


THE  ERIE  CANAL. 

The  Erie  Canal  also  presents  a  great  opportunity  for  the  Company. 

Between  $5,000,000  and  $6,000,000  have  already  been  expended  on  the  work, 
$10,000,000  having  been  set  aside  by  the  State  as  a  first  appropriation.  During  the  next 
two  or  three  months  the  balance  of  $4,000,000  of  this  sum  will  have  to  be  paid  out  for 
work  done,  and  a  further  sum  set  aside  for  new  contracts. 

The  engineers’  estimate  of  the  total  cost  of  the  enterprise  is  $100,000,000,  and 
there  is  little  doubt  but  that  the  whole  of  this  amount  will  be  expended. 

The  work  offers  good  opportunities  for  the  employment  of  the  Frtjhling  System. 


THE  MISSISSIPPI  RIVER  COMMISSION. 

This  Commission  was  appointed  many  years  ago  by  the  United  States  Govern¬ 
ment,  and  has  since  been  in  almost  continual  session  for  the  study  of  the  problem 
presented  by  the  Mississippi  River  in  the  obstructions  continually  arising  throughout  its 
navigable  course. 

Enormous  amounts  of  money  are  annually  spent  in  the  attempts  to  keep  the 
necessary  channels  open.  The  rapidity  with  which  the  sand  and  other  materials  accumu¬ 
late  renders  the  work  of  the  Commission  extremely  onerous.  The  fact  that  it  is  sand 
and  silt  which  causes  so  much  trouble  in  this  instance  immediately  suggests  the  use  of 
the  Pruhling  System  as  a  means  whereby  these  accumulations  can  be  dealt  with.  The 
matter  will  be  investigated. 


THE  AMBROSE  CHANNEL  CONTRACT  IN  NEW  YORK  HARBOUR. 

The  contract  for  the  dredging  of  the  East  or  Ambrose  channel  in  New  York 
Harbour  called  for  the  removal  of  no  less  than  45,000,000  cubic  yards  of  material,  or  some 
60,000,000  tons — a  work  of  international  importance.  The  present  channel  is  danger¬ 
ously  narrow  and  shallow,  and  provides  absolutely  inadequate  accommodation  for  the 
traffic  using  it. 

ARTICLE  FROM  “  THE  SCIENTIFIC  AMERICAN  ”  ON  THE  FRUHLING  SYSTEM. 
COMMENTS  ON  THE  APPLICABILITY  OF  THE  FRUHLING 
SYSTEM  TO  THE  WORK  IN  NEW  YORK  HARBOUR. 

Showing  the  enormous  extent  of  this  contract,  it  may  be  mentioned  that  the 
total  amount  of  material  to  be  removed  for  the  completion  of  the  channel  exceeds  by 
SIX  TIMES  THE  TOTAL  AMOUNT  ANNUALLY  DREDGED  FROM  THE  GREAT  ENGLISH  PORTS  OF 

Manchester,  Hull,  Liverpool,  the  Clyde,  and  London. 

One  of  the  Fruhling  dredges  built  for  the  German  Government  within  the  last 
year  is  the  largest  dredger  in  the  world. 

The  following  extract  from  the  Scientific  American  is  here  quoted  and  comment 
made,  showing  what  would  hqve  been  the  result  of  applying  such  a  vessel  to  the  New 
York  contract. 


17 


Extract  from  the  “Scientific  American”  for  September  2nd,  1905. 

■  A  GIANT  DREDGE  (THE  FRUHLING  DREDGER). 

“  The  gigantic  dredger  represented  in  the  accompanying  photograph  has  recently 
been  completed  by  F.  Schichau,  of  Elbing  and  Danzig,  Germany,  for  the  Imperial  Navy, 
and  it  is  intended  for  maintaining  the  channel  of  the  Jade  River  at  a  convenient  depth. 

The  dredges  available  in  the  Prussian  seaports,  up  to  this  time,  had  proved  unable 
to  deal  with  the  Jade  Channel,  which  is  rather  shallow  for  the  new,  large  draft  German 
liners. 

This  dredge,  which  is  the  biggest  in  the  world,  sailed  for  Wilhelmshaven  after  a 
short  test  of  its  engines  made  in  the  Danzig  shipyards,  and  in  the  latter  part  of  December 
rapidly  accomplished  its  trial  dredging  with  splendid  results. 

Whereas,  the  contracts  called  for  an  hourly  output  of  Jf.,680  cubic  yards  in  soft 
ground,  the  dredge  by  far  exceeded  this  figure,  readily  dealing  with  6,500  cubic 
YARDS  (or  about  7,700  tons)  per  hour,  instead  of  4^,0 80,  as  stipulated.^’ 

(Note. — The  dredgers  Mills  and  Thomas,  the  contractors’  dredgers  on  the 
Ambrose  Channel  contract  in  New  York  Harbor,  which  are  only  slightly 
smaller  than  the  dredge  now  described,  together  dredged  an  average  amount 
PER  DAY  OF  ONLY  11,000  cubic  yards  during  the  year  1904  in  easy  sand,  or 
ONLY  ABOUT  ONE-HALF  AS  MUCH  AGAIN  AS  THE  FrUHLING  DrEDGER  RAISED  IN 
ONE  HOUR  BY  ITSELF.) 

“In  heavy  sandy  ground,  of  specific  weight  1.96,  the  dredge  excavated  4,680  cubic 
yards  per  hour,  65  per  cent,  of  solid  ground  being  raised  by  the  pressure  pipes.” 

(Note. — The  percentage  of  solids  raised  with  the  ordinary  suction  system 
RARELY  exceeds  10  per  cent.) 

“  As  regards  the  speed  stipulated  by  contract,  this  had  to  be  8  knots  with  full  loads 
and  tanks  pumped  full.  The  mean  speed  during  a  run  of  several  hours’  duration  was, 
however,  10  knots  instead  of  8  knots,  showing  an  enormous  increase  in  the  performance 
of  the  dredge.  The  coal  consumption  was  extremely  favorable,  being  0.85  pounds  per 
horse  power  per  hour. 

Owing  to  this  increase  in  output  and  speed  the  dredge  is  able  to  raise  and  re¬ 
move  AS  much  as  31,200  cubic  yards  of  soil  in  one  day,  corresponding  to  a  yearly 
OUTPUT  OF  7,800,000  CUBIC  YARDS  IN  250  WORKING  DAYS.” 

[Note. — The  latest  Government  figures,  issued  in  October,  1905,  show  that 
the  Mills  and  Thomas  (referred  to  above)  together  with  the  two  Government 
DREDGERS,  the  Manhattan  and  the  Atlantic,  which  are  of  nearly  the  same  size 
as  the  two  contractors’  dredgers,  dredge  and  remove  some  650,000  cubic  yards 
per  month,  working  night  and  day.  These  figures  show  that  these  four 
DREDGERS  WOULD  IN  A  FULL  YEAR  OF  365  DAYS  OF  24  HOURS  EACH,  ONLY  JUST 
EQUAL  THE  WORK  OF  THE  ONE  FrUHLING  DrEDGE  IN  250  DAYS,  i.  6.,  7,800,000.] 
(And,  in  addition,  it  must  be  remembered  that  these  four  dredgers  cost 
$1,700,000  to  build,  whereas  the  FrUHLING  dredger  DESCRIBED  COST  ONLY  SOME 
$350,000.) 


18 


“Each  cubic  yard  of  soil  raised  costs  accordingly  less  than  0.6  of  a  cent, 

INCLUDING  ALLOWANCE  FOR  THE  DEPRECIATION  OF  THE  DREDGE.” 

(Note. — The  average  cost  of  dredging  and  removing  soil  on  the  New  York 
Harbor  contract  to  the  Government  and  the  contractors  is  about  5.50  cents  per 
cubic  yard.) 

“  This  result  is  quite  unique  and  much  more  satisfactory  than  any  of  the  figures 
so  far  realized,  as  the  harbor  dredges  so  far  known  raised  each  cubic  yard  of  soil  at 
an  average  cost  of  9.6  cents.  The  Schichau  shipyards,  we  are  informed,  have  secured 
contracts  for  a  number  of  these  novel  dredges,  especially  for  foreign  ports.’^ 

(Note. — Simple  calculations  show  that  had  the  Government  constructed  one 
Fruhling  dredger,  such  as  is  described,  and  placed  it  on  the  New  York  contract, 


it  would  have  saved: 

In  initial  cost  of  construction .  $1,350,000 

In  working  expenses  on  the  total  amount  of  material 

to  be  removed  no  less  than .  $2,500,000 


And  would  have  been  able  to  complete  the  work  in  less  time. 

PRICES  PAID  IN  CONTRACT  FOR  DREDGING  WORK. 

« 

Prices  paid  for  dredging  work  vary  considerably.  For  work  in  light  materials 
such  as  sand  or  silt  from  10  cents  to  30  cents  per  cubic  yard  may  be  obtained  and  in 
cases  of  pressing  urgency  as  much  as  50  cents  or  even  $1  per  cubic  yard  has  been  paid. 
The  amount  to  be  dredged  and  the  conditions  under  which  dredging  has  to  be  carried 
out  influence  the  price.  For  instance  in  the  great  work  for  dredging  the  channel  in 
New  York  Harbour  only  9  cents  per  cubic  yard  was  paid.  For  work  in  the  heavier 
materials  it  is  even  harder  to  give  any  set  table  of  prices.  It  is  only  safe  to  say  that 
from  30  cents  up  to  almost  any  amount  is  paid.  As  much  as  $3  per  cubic  yard  was  paid 
in  New  York  for  the  dredging  of  some  4,000  cubic  yards  of  mud.  The  profits  made  out 
of  this  work  must  have  been  enormous,  as  even  at  50  cents  a  profit  of  nearly  30  cents 
per  cubic  yard  would  have  been  realized — if  not  more  than  that.  But  in  such  small  con¬ 
tracts  the  price  has  necessarily  to  be  high  to  induce  contractors  to  undertake  the  work. 


The  following  table,  compiled  from  the  Annual  Report  of  the  Chief  of  Engineers 
of  the  United  States  Army,  which  gives  the  cost  and  object  of  some  of  the  most  impor¬ 
tant  dredging  works  in  America,  serves  very  strikingly  to  show  the  great  sums  of  money 
expended  on  a  branch  of  the  countr3'’s  domestic  affairs  to  which  so  little  of  its  citizens’ 
attention  is  given;  and,  in  addition,  affords  further  proof  of  the  unrivalled  opportunities 
and  the  vast  field  awaiting  this  Company. 

Boston  (Mass.).  For  a  channel  1,000'  wide  by  27'  deep;  project  adopted 


in  1892 .  $1,488,751 

For  a  channel  1,200'  wide  by  30'  deep;  adopted  in  1899 .  455,000 

For  a  channel  1,200'  wide  by  35'  deep;  adopted  in  1902 .  7,994,248 

New  Haven  (Conn.).  For  a  channel  400'  wide  by  20'  deep;  4  miles 

long  (3,287,000  cu.  yds.) .  345,000 

Baltimore  (Md.).  For  maintenance  of  a  channel  30'  deep;  adopted  in 

1896  (annual  payment  of) .  60,000 


19 


Charleston  (S.  C.).  For  a  channel  600'  wide  by  26'  deep;  adopted  in 

1899  (between) .  $4,000,000  and 

5,000,000 

Chesapeake  Bay.  For  a  channel  100'  wide  by  10'  deep;  adopted  in 

1899 .  274,310 

Great  Lakes.  For  a  channel  between  Chicago,  Duluth  and  Buffalo, 

300'  wide  by  20'  deep;  adopted  in  1892 .  ...  3,340,000 

Reclamation  work.  Southern  Idaho.  Snake  River  Valley,  and  a  canal 

69  miles  long  with  80'  width  at  bottom,  adopted  1903 .  6,000,000 

Cleveland  (Ohio).  For  a  channel  to  be  dredged  to  a  depth  of  25'; 

adopted  in  1899 .  478,400 

Galveston  (Tex.).  A  ship  channel  100'  wide  by  25'  deep,  and  a  channel 

in  the  harbor  600'  wide  and  25'  deep;  adopted  in  1903 .  4,000,000 

And  an  annual  payment  for  maintenance  work  of .  100,000 

Portland  Harbour  (Me.).  Dredging  to  a  depth  of  30';  adopted  in  1896  946,250 

San  Diego  Harbour  (Cal.).  For  a  channel  500'  wide  and  24'  deep; 

adopted  in  1900 .  542,850 

Mississippi  River  Commission.  For  a  channel  1,000'  wide  and  35' 

deep;  adopted  in  1900 .  6,000,000 

Construction  of  tugs  for  upkeep,  &c. ;  an  annual  payment  of. .  150,000 

Mississippi.  Maintenance  work  in  South  Pass  Channel;  adopted  in 

1889;  an  annual  payment  of .  100,000 

(This  being  only  an  infinitesimal  portion  of  the  amount  annually 
expended.) 

Tampa  Bay  (Fla.).  For  a  channel  500'  wide  by  27'  deep;  adopted  in 

1899  .  750,000 

Diverting  of  Yazoo  River  and  Vicksburg  Harbour  (Miss.).  Improve¬ 
ment,  excavation  of  5,836,366  cu.  yds.  earth .  1,200,000 

Norfolk  (Va.).  For  a  channel  450'  wide  and  28'  deep;  adopted  1899.  359,516 

WiMPAH  Bay  (S.  C.).  For  construction  of  ietties  and  dredging;  adopted 

1902 .  1,848,000 

Mobile  Harbor  (Ala.).  A  channel  100'  wide  by  23'  deep;  adopted  in 

1902  .  1,640,000 

And  a  channel  300'  wide  and  30'  deep .  91,250 

Pawtucket  River  (R.  L).  For  a  channel  100'  wide  and  12'  deep; 

originally  adopted  in  1883  and  further  revised  1904 .  382,500 

Passaic  River  (N.  J.).  For  a  channel  200'  wide  by  10'  deep;  adopted 

1892 .  547,697 

Albemarle  Sound  (N.  C.).  For  a  channel  80'  wide  by  9'  deep;  adopted 

in  1890 .  306,667 

Pensacola  (Fla.).  For  a  channel  500'  wide  by  30'  deep;  adopted  in  1902.  220,000 

(part  dredge  construction.) 

Philadelphia  (Penn.).  For  a  channel  600'  feet  wide  by  30'  deep; 

adopted  in  1899 .  6,810,000 

St.  John’s  River  (Fla.).  Dredge  construction  and  for  dredging;  adopted 

in  1902 .  1,450,000 


20 


Savannah  Harbour  (Ga.).  For  Harbour  Improvement;  adopted  in 

1896 .  $992,250 

Keweewan  Bay  to  Lake  Superior  (Mich.).  For  caual  construction, 

width  70',  depth  16';  adopted  in  1^96 .  1,115,000 

Detroit  River  (Mich.).  For  a  channel  600'  wide  and  20'  deep  between 

Detroit  and  Lake  Erie;  adopted  in  1892 .  1,554,000 

Revised  and  additional  scheme  adopted  in  1902  for  a  channel 

600'  wide  by  21'  deep .  2,200,000 

Irrigation  lake  and  canals  at  Roosevelt  (Arizona),  adopted  1901 .  31,500,000 


CONSTRUCTION  OF  DREDGERS  AND  WORK  FOR  THE  COMPANY. 

A  number  of  contracts  for  dredging  work  have  already  been  offered  on  which  the 
Fruhling  system  could  be  profitably  employed,  and  contractors  have  everywhere  evinced 
great  interest  in  the  system  and  have  recognized  its  merits.  It  h:3s  not  been  deemed 
advisable,  however,  to  make  any  decision  as  to  what  work  the  Company  would  under¬ 
take  when  formed,  for  the  reason  that  the  most  minute  details  of  any  such  work  must 
be  gone  into  with  an  amount  of  care  and  thoroughness  it  would  be  impossible  to  afford 
under  the  present  circumstances. 

Investigations  of  the  conditions  under  which  dredging  operations  are  carried  out 
and  the  positions  of  various  contractors  in  relation  to  their  progress  in  contracts  under¬ 
taken  by  them  have  been  made,  and  it  is  certain  that  the  Company  will  when  formed  be 
able  to  obtain  all  tbe  work  it  can  conveniently  handle.  In  fact  it  may  be  said  that  the 
amount  of  work  the  Company  will  be  able  to  secure  will  only  be  limited  by  the  amount 
of  the  Company’s  resources  for  the  building  of  Fruhling  dredgers. 

In  view  of  the  fact  that  it  will  in  any  case  be  necessary  that  the  Company  shall 
know  tbe  cost  of  dredger  construction  plans  and  specifications,  a  model  of  a  large  Fruh¬ 
ling  dredger  has  been  prepared  by  Mr.  William  A.  Fairburn,  the  Superintending 
Engineer  to  the  Southern  Pacific  Atlantic  Steamship  Lines.  Mr.  Fairburn  has  the 
highest  reputation  as  a  designer  of  all  types  of  steamships,  and  the  two  largest  freight¬ 
carrying  vessels  in  the  world— tbe  Minnesota  and  the  Dakota  (among  many  other  large 
vessels)  were  designed  by  him.  Moreover,  Mr.  Fairburn  has  introduced  methods  into 
steamship  construction  by  which  the  cost  of  construction  is  very  materially  reduced 
without  any  sacrifice  of  efficiency.  Mr.  Fairburn  has  also  had  considerable  experience 
in  dredging  matters,  is  thoroughly  conversant  with  the  main  features  of  the  Fruhling 
system,  and  is,  in  addition,  impressed  with  its  merits. 

Before  the  completion  of  the  plans  now  in  course  of  preparation  by  Mr.  Fairburn, 
Herr  Frubling  would  be  consulted  and  the  plans  submitted  to  him.  Herr  Fruhling 
would  prepare  the  specifications  and  plans  for  the  construction  of  his  dredging  head  and 
apparatus  in  accordance  with  the  requirements  of  the  hull  designed  by  Mr.  Fairburn. 
A  dredger  built  on  the  plans  prepared  by  two  such  experts  would  undoubtedly  be  the 
best  obtainable. 

The  cost  of  the  vessel  Mr.  Fairburn  proposes  would  be  $275,000.  The  vessel  would 
be  a  “  self -containing  ”  dredge  with  a  hopper  capacity  of  2,000  tons  of  dredged  material. 
The  dredging  capacity  would  be  5,000  cubic  yards  per  hour  in  good  material.  In  difficult 


\ 


21 


material  Mr.  Fairburn  is  of  opinion  some  8,000  cubic  yards  could  be  dealt  with  in  a  day 
of  ten  working  hours,  i.  e.,  200,000  cubic  yards  per  month  of  25  days. 

The  cost  of  operating  the  difficult  material  alluded  to  per  month  would  be  $6,200 
per  month.  The  various  items  of  expense  being  estimated  as  follows: 


Pay  roll  of  complement .  $937  00 

Coal .  1,125  00 

Food .  255  00 

Oil,  water  and  stores .  175  00 

Kepairs .  300  00 

Superintendent .  200  00 

Office  expenses .  400  00 

Depreciation .  1,525  00 

Insurance  and  miscellaneous  expenses .  283  00 


Total  cost  op  operating  for  One  Month .  5,200  00 


The  figures  for  depreciation  are  based  on  the  life  of  the  boat  being  fifteen  years — 
which  is  much  less  than  the  true  life  of  the  vessel  should  actually  be.  The  other  items 
in  the  foi'egoing  table  are  estimated  by  Mr.  Fairburn  out  of  his  great  experience  in  the 
designing  construction  and  management  of  steamships. 

The  plans,  &c.,  of  the  dredger  described  should  be  of  great  value  to  the  Company. 
It  is  not,  of  course,  to  be  taken  that  the  building  of  this  dredger  should  be  proceeded 
with  as  soon  as  the  Company  is  formed.  It  would,  of  course,  be  quite  possible  to  build 
a  dredger  on  the  Fruhling  system  for  a  sum  much  below  that  needed  for  the  construc¬ 
tion  of  such  a  vessel  as  is  described  hereinbefore.  As  instancing  this  fact  the  dredger 
reported  on  by  Messrs.  Flannery,  Baggallay  &  Johnson,  of  London,  England  (in  their 
report  attached  to  this  proposal),  i.  e.,  the  Nicolaus,  engaged  in  maintaining  the  entrance 
to  the  Kiel  Canal,  cost  only  some  $100,000  to  build,  and  is  capable  of  raising  nearly  3,000 
cubic  yards  per  hour,  but  has  hopper  capacity  for  only  some  500  tons,  and  is  therefore 
much  smaller  than  the  vessel  Mr.  Fairburn  is  designing.  It  would  be  possible  to  build 
a  Fruhling  dredger  without  any  hopper  capacity  capable  of  doing  excellent  work  at 
1,000  to  1,500  cubic  yards  per  hour,  at  a  cost  of  $75,000.  The  Company’s  first 
dredger  will  be  constructed  to  meet  the  requirements  of  work  undertaken,  and  will  be 
dominated  by  the  amount  of  funds  at  the  Company’s  disposal.  Such  a  vessel  as  is 
described  would,  however,  be  capable  of  undertaking  work  of  the  class  it  is  desired  to 
obtain,  that  is  to  say,  of  work  of  importance  and  magnitude.  In  such  work  the  vessel 
would  earn  large  profits. 

It  is  necessary,  however,  that  it  Should  be  well  understood  that  it  is  not  claimed 
for  the  Fruhling  System  that  it  is  capable  of  undertaking  dredging  work  in  all  sorts 
of  materials.  As  has  been  previously  pointed  out  herein  there  are  various  kinds  of 
materials  such  as  heavy  clay  and  rocks  which  it  is  impossible  to  deal  with  under  any 
circumstances  by  means  of  the  suction  system.  To  deal  with  these  materials  dredgers 
of  the  clam-shell,  bucket  or  dipper  type  must  be  employed.  In  considering  tbe  suit¬ 
ability  of  contracts  therefore  it  will  be  necessary  to  make  the  most  careful  investigations 
with  a  view  to  ascertaining  as  nearly  as  is  possible  the  exact  proportions  of  the  materials 


/ 


22 


with  which  the  Fruhling  system  can  or  cannot  deal.  Naturally  those  contracts  offering 
the  largest  proportions  of  work  in  mud  and  sand  will  be  first  considered.  It  may  very 
possibly  happen  that  a  contract  will  show  85%  of  mud  and  sand  and  15%  of  rocks  and 
heavy  clay.  In  such  cases  it  is  the  custom  of  the  Government  to  offer  the  contract 
usually  in  two  portions,  i.  e.,  the  hard  and  the  soft  work,  at  two  different  prices.  If  it 
is  considered  advisable  to  make  an  offer  for  the  whole  of  the  work  in  both  soft  and  hard 
materials  the  Company  will  either  hire  or  build  dredgers  for  the  work  on  the  hard 
materials.  In  cases  where  the  whole  work  must  be  tendered  for,  very  careful  figuring 
is  necessary,  and  the  advice  of  the  best  expert  obtainable  of  the  greatest  importance. 
In  these  cases  Herr  Fruhling  will  be  of  inestimable  value  to  the  Company  with  his  great 
dredging  knowledge  and  experience. 

The  intentions  of  the  proposed  Company  with  regard  to  construction  of  plant 
have  only  been  touched  upon  herein  in  the  most  general  terms,  for  the  reason  that  the 
policy  of  the  Company  will  be  in  the  hands  of  its  Stockholders  who  will  from  the  outset 
have  perfect  freedom  in  deciding  the  work  that  will  be  taken  up  and  the  work  that  will 
be  avoided. 

The  machines  it  is  proposed  to  purchase  may  be  divided  into  two  classes — Main 
and  Auxiliary.  The  main  devices  are  Thk  Fruhling  Patent  Suction  Pipe  Dredging 
Head  Attachment.  The  auxiliary  machines  consist  of  various  adaptations  of  the  main 
device  for  work  under  extraordinary  conditions  As  instances,  it  may  be  said  that  Herr 
Fruhling  has  invented  means  for  reversing  the  dredging  head  and  dredging  in  a  diagonal 
instead  of  a  longitudinal  manner.  Herr  Fruhling  has  also  invented  a  system  of  piping 
for  the  scouring  out  of  the  holds  of  dredging  vessels.  This  system  has  been  fitted  to 
each  of  the  dredgers  built  for  the  German  Government,  with  very  marked  success. 


PROSPECTS  OF  THE  COMPANY. 

THE  COMPANY  OWNING  THE  FRUHLING  SYSTEM  WILL  BE  ABLE  TO 
UNDERTAKE  DREDGING  WORK  AT  A  LOWER  FIGURE  THAN  WILL  BE  POS¬ 
SIBLE  TO  ANY  COMPETITOR  AND  AT  THE  SAME  TIME  TO  EARN  LARGER 
PROFITS. 


COPIES  OF  REPORTS,  &c. 

Certified  copies  of  the  report  by  Messrs.  Flannery,  Baggallay  and  Johnson  and  of 
the  certificate  by  Herr  Scholer  on  the  Fruhling  System  may  be  seen  at  No.  15  William 
Street,  New  York  (City),  the  office  of  Mr.  W.  Donald  Angier.  The  original  of  the 
address  on  the  Fruhling  system  given  by  Herr  Scholer  at  the  meeting  of  the  Inter¬ 
national  Navigation  Congress  at  Dusseldorf  is  in  Germany. 


REPORTS. 


25 


FRUHLINQ  SYSTEM. 

The  following  certificate  shows  the  work  done  by  the  system  on  the  Kiel  Canal  in 
Germany,  and  the  high  opinion  in  which  it  is  there  held  hy  authorities  most  competent 
to  judge : 

KIEL,  12th  March,  1903.— This  is  to  certify  that  the  dredger 
JVicolaus  in  the  Emperor  William  Canal  from  the  15th  October,  1901,  to 
the  1st  March,  1903,  has  dredged  in  700  working  hours  1,350,000  tons 
of  sand,  mnd  and  silt,  and  has  transported  and  discharged  this  material 
for  a  distance  of  1.5  miles  in  1,450  hours.  The  average  cost  of  the  above 
work  (including  transport)  was  three-fifths  of  a  penny  per  ton  (about  one 
cent  in  U.  S.  A.  currency). 

After  carefully  watching  the  work  done  by  the  Mcolaus  during  the 
above  period  I  am  able  to  say  that,  in  my  opinion,  the  Fruhling  system  is 
the  MOST  RELIABLE,  ECONOMICAL  AND  EFFECTIVE  system  of 
maintenance  dredging  I  have  seen. 

(Sig^ned)  ^CUOLER. 

Chief  Engineer  to  the  German  Gov.,  Member  of  the 
Imperial  Canal  Commission  at  Kiel. 


27 


Report  No.  1. 


Report  made  by 

FLANNERY,  BAGGALLAY  &  JOHNSON, 

Consulting  Engineers. 

Sir  Fortescue  Flannery,  M.I.C.E.,  M.I.M.E, 
Robert  Baggallay,  M.I.M.E. 

Alexander  B.  Johnson,  M.I.N.A. 

Herbert  B.  Gregson,  Wh.Sc.,  A.M.I.C.E.,  M.I.N.A. 
Ernest  C.  Given,  A.M.I.C.E.,  A.M.Mech.E. 


FRUHLING  SYSTEM. 
Steam  Dredger  “Nicolaus.” 


To  W.  Donald  Angier. 
Dear  Sir: 


9  Fenchurch  Street, 

London, 

October  Gth,  1902. 


At  your  request  we  proceeded  to  Hamburg,  and  from  there  to  Brunsbuttel,  at  tbe 
Elbe  entrance  of  the  Kaiser  William  or  Kiel  Canal,  to  inspect  and  report  on  the  steam 
dredger  “  Nicolaus,”  fitted  with  dredging  system  by  Herr  0.  Fruhling,  of  Brunswick. 

We  visited  vessel  on  the  30th  September,  1902,  and  found  that  the  steam  dredger 
“Nicolaus”  had  been  constructed  specially  for  working  in  and  at  the  entrance  of  the 
Kaiser  Wilhelm  Canal,  her  dimensions  being  about  47  metres  (155  feet)  long  by  8^  metres 
(28  feet)  wide,  these  dimensions  being  the  largest  suitable  for  manoeuvring  and  turning 
vessel  round  in  the  Canal. 

On  deck  the  machinery  consists  of  a  powerful  double  winch  forward,  fitted  for  the 
purpose  of  working  two  anchors  to  pull  vessel  forward,  should  it  be  necessary  to  work 
with  anchors  and  chains  instead  of  propellers;  the  anchors  can  also  be  used  to  aid  pro¬ 
pellers  in  forcing  vessel  forward  should  very  stiff  bottom  be  encountered.  There  are 
also  four  winches — two  forward  and  two  aft — for  working  the  hoppers  when  this  system 
of  emptying  vessel  is  used.  Also  a  powerful  crane  aft  for  raising  and  lowering  the 


28 


dredging  gear.  This  crane  is  also  designed  for  the  purpose  of  raising  wreckage,  etc.,  and 
strongly  ties  the  two  halves  of  the  stern  of  the  vessel  together.  In  addition  there  are 
several  valves,  valve-rods,  etc.,  led  through  the  deck  for  manipulating  the  valves  in  the 
piping  system. 

Vessel  is  constructed  as  a  hopper  dredger,  and  has  three  compartments  for 
holding  the  dredged  material,  one  forward  of  200  cubic  meters  (201.6  cubic  yards) 
capacity,  and  two  aft,  one  on  each  side  of  the  gap,  of  100  cubic  metres  (130.8  cubic 
yards)  capacity  each,  or  a  total  capacity  of  400  cubic  metres  (523.2  cubic  yards).  The 
boilers  and  machinery  are  situated  amidships,  and  this  arrangement  of  holds  permits  of 
vessel  always  being  kept  on  an  even  keel. 

The  vessel  is  fitted  with  two  sets  of  engines  of  120  h.p.  each,  to  drive  the  twin 
screws  for  propelling  vessel,  and  in  addition  in  the  machinery  department  are:  A 
compound  engine  of  150  h.p.,  which  makes  about  250  revolutions  per  minute  when 
driving  the  centrifugal  pump  for  dredging;  a  Blake  pump  12"  X  IS^"  X  14"  X  12"  for 
delivering  water  under  pressure  to  dredger  head,  to  scour  out  holds  if  necessary,  or  to 
be  used  for  salvage  operations;  a  dynamo,  and  the  usual  auxiliary  machinery.  Steam 
is  supplied  by  two  boilers  of  the  ordinary  marine  type,  working  at  a  pressure  of  8  atmos¬ 
pheres.  The  suction  pipe  has  a  diameter  of  I5f".  We  found  the  whole  of  the  machinery 
apparently  in  very  good  condition. 

The  piping  system  of  vessel  is,  in  our  opinion,  very  complete,  and  should  the 
dredged  material  become  too  solid  to  be  pumped  out  of  the  holds,  it  can  be  loosened 
and  softened  by  means  of  opening  the  valves,  or,  should  this  not  prove  effective,  by 
putting  water  urrder  pressure  through  other  pipes  by  means  of  the  Blake  pump.  This 
arrangement  is  also  patented  by  Herr  Fruhling. 

The  special  dredging  apparatus  invented  by  Herr  0.  Fruhling  consists  principally 
of  a  strong  box  girder,  which  contains  the  suction  pipe,  and  is  attached  to  vessel  and 
held  in  position  at  the  forward  end  of  gap  by  two  trunnions  working  in  bearings.  At 
the  after  end  of  the  box  girder  is  the  specially-designed  dredger  head,  which  is  raised  or 
lowered  as  required  through  the  gap  in  vessel  by  means  of  the  crane  at  after  end  of  ves¬ 
sel.  The  dredger  head,  which  in  this  case  is  about  metres  (11^  feet)  wide,  consists  of 
two  principal  parts.  The  forward  or  front  part  is  in  the  form  of  a  bucket  or  scoop, 
having  several  sharp  prongs  or  points  on  the  edge.  This,  on  being  drawn  forward,  scoops 
up  the  material  to  be  dredged;  and  should  the  material  dredged  be  solid  the  prongs  or 
points  assist  to  atomize  or  split  it  up.  The  after  or  back  part  consists  of  a  chamber 
which  is  termed  the  mixing  chamber,  into  which  the  material  dredged  by  the  bucket  is 
forced.  It  is  from  this  mixing  chamber  that  the  dredged  material  is  pumped. 

The  mixing  is  done  by  means  of  admitting  water  at  the  upper  end  of  the  box  girder, 
through  which  it  flows  on  the  outside  of  the  suction  pipe  into  the  mixing  chamber,  and 
the  amount  of  water  is  controlled  by  means  of  levers  from  the  deck. 

Should  the  ground  to  be  dredged  be  stiff  soil,  and  require  more  atomizing  or  splitting 
up  than  can  be  done  by  the  bucket  and  mixing  as  above  mentioned,  it  can  be  loosened 
by  the  means  of  water  under  pressure,  which  is  forced  by  the  Blake  pump  through  three 
pipes  laid  side  by  side  and  secured  on  top  of  the  box  girder,  and  which  lead  through 
smaller  pipes  into  the  prongs  or  points  at  the  edge  of  bucket,  and  into  the  mixing 


29 


chambers.  But  ia  the  case  of  the  Nicolaus  the  material  dredged  off  Brunsbuttel  has 
required  very  little  mixing  water. 

Vessel  can  be  discharged  either  by  the  hopper  or  by  the  dredging  pump,  and  pipes 
are  arranged  so  that  the  dredged  material  can  be  discharged  into  hopper  barges  or  on  to 
the  banks  of  the  Canal.  This  arrangement  also  enables  vessel  to  be  more  useful  as  a 
salvage  boat,  as  the  holds  can  be  very  rapidly  filled  or  emptied,  as  desired. 

In  our  opinion  the  Fruhling  system  has  several  great  advantages,  among  which 
are  the  following,  viz. : 

(1.)  Vessel  is  propelled  while  dredging,  and  therefore  under  control  the  whole  time. 
This  is  of  great  importance  in  narrow  waters  or  at  entrance  to  docks,  etc.,  especially  where 
there  is  much  traffic;  and  in  addition,  as  vessel  has  not  to  be  anchored  or  moored,  much 
time  is  saved  by  not  having  to  moor  and  unmoor. 

(2.)  Vessel  being  propelled  while  dredging  with  this  system,  the  ground  is  cut  or 
scooped  up  level  to  any  required  depth,  thus  obviating  the  risk  of  forming  holes  in  the 
neighborhood  of  banks,  etc.,  or  of  undermining  them. 

(3.)  Vessel  being  propelled  while  dredging  can  cut  or  scoop  up  the  ground  for  a 
width  of  11.48  feet  in  any  required  direction  till  holes  are  filled,  and  can  after  discharg¬ 
ing  same  by  means  of  landmarks,  etc.,  return  and  continue  the  levelling  process. 

(4.)  That  by  the  construction  of  the  dredging  head  the  Fruhling  system  combines 
several  good  points  of  the  suction  and  bucket  dredgers,  the  principal  and  most  important 
of  which  is  the  power  of  dealing  by  suction  with  soil  heavier  and  more  clay-like  than 
has  hitherto  been  attempted  successfully  with  a  suction  dredger. 

(5.)  That  the  amount  of  water  pumped  up  is  under  the  control  of  those  working 
the  vessel,  and  that  it  is  not  necessary  to  pump  up  more  water  than  is  required  (in  the 
case  of  mud)  to  moisten  the  mud  for  effective  pumping. 

(6.)  That  the  material  dredged  containing  only  a  small  percentage  of  water,  no 
time  is  wasted  in  waiting  for  material  to  settle  or  extra  pumping  to  allow  water  to 
overflow  from  the  holds,  but  as  soon  as  holds  are  full  vessel  can  proceed  to  the  dumping 
ground, 

(7.)  The  small  number  of  working  parts,  so  that  wear  and  tear  and  repairs  are 
reduced  to  a  minimum. 

(8.)  The  adaptability  of  the  system  to  meet  various  local  requirements. 

We  are  informed  by  the  Government  Engineer  in  charge  of  the  Brunsbuttell 
district  that  previous  to  the  Nicolaus  commencing  work,  it  took  a  large  bucket  dredger 
and  three  steam  hopper  lighters  working  night  and  day  to  keep  the  channel  clear, 
whereas  the  Nicolaus  now  does  the  work  more  effectively  and  works  only  ten  hours 
per  day. 

From  official  accounts  we  find  that  Nicolaus  has  done  the  following  work. 


VIZ 


30 


Date. 

Time 

Dredging. 

Time 
Trans¬ 
porting 
and  Dis¬ 
charging. 

Total  Time. 

Quantity 
Dredged  and 
Transported. 

Total  Cost  of 
Wages,  Stores 
and  Upkeep. 

Cost 

per 

Cubic 

Metre. 

Equiva¬ 
lent  in 
U.  S.  A. 
Currency 
Cost  per 
Cu.  Metre. 

Equiva¬ 
lent  in 

U.  S.  A. 
Currency 
Cost  per 
Cu.  Yard. 

Hrs.  Mins. 

Hrs.  Mins. 

Hrs.  Mins. 

Cubic  Metres. 

Marks. 

Pfen. 

Cents. 

Cents. 

From 

Oct. 

556,950 

39,533.80 

14th, 

1901, 

to 

Aug. 

445  59 

950  57 

1,396  56 

7.1 

.986 

.750 

1st, 

1902. 

Cubic  Yards. 

Dollars. 

728,490.6 

$9,670,68 

In  the  above  table  the  transporting  from  October  14th,  1901,  to  April  13th,  1902, 
was  for  a  distance  of  about  3  kilometres,  and  from  April  14th,  1902,  to  August  1st,  1902, 
was  principally  inside  the  Canal,  and  transporting  was  for  a  distance  of  12  kilometres, 
and  the  dredged  material  was  discharged  on  land  by  means  of  the  dredging  pump. 

At  about  11.45  a.m.  on  30th  September,  1902,  vessel  unmoored  in  our  presence 
from  the  quay  and  commenced  dredging  in  inner  harbor,  to  illustrate  the  working. 
Vessel  then  entered  lock  and  was  locked  out  of  Canal,  proceeded  about  3  kilometres, 
where  the  dredged  material  was  discharged,  the  forward  compartment  of  200  cubic 
metres  being  dumped  through  hoppers  in  30  seconds,  and  the  two  after  compartments 
of  100  cubic  metres  each  being  pumped  overboard  in  4^  minutes.  Vessel  then 
returned  to  outer  harbour  and  filled  all  three  compartments  in  16  minutes  with  mud, 
containing  about  15  per  cent,  of  water;  then  proceeded  about  3  kilometres,  and 
dumped  the  whole  cargo  in  30  seconds.  Vessel  then  returned  to  the  harbor  at 
1.45  p.m.  We  requested  to  see  the  whole  of  the  compartments  filled  and  pumped  over¬ 
board  or  discharged  on  land.  It  was  explained  that  the  orifices  to  valves  in  the  forward 
compartment  had  been  blocked  up  with  wood  plugs  by  order  of  the  authorities,  as  they 
were  not  required  to  be  worked  at  present.  But  the  Government  Engineer  of  the  dis¬ 
trict  very  courteously  and  kindly  had  the  plugs  removed. 

At  3.52  p.m.  vessel  was  cast  off  from  quay  and  at  once  commenced  dredging  in 
inner  harbor;  all  three  compartments  were  filled  in  12^  minutes  with  black  mud  and 
fine  sand;  vessel  then  steamed  along  Canal  for  a  distance  of  12  kilometres,  having  to 
ease  down  when  passing  four  steamers,  and  arriving  opposite  jetty  at  4.52,  or  in  exactly 
one  hour;  vpssel  was  then  turned  round  in  the  width  of  the  Canal,  the  twin  screws 
enabling  this  manoeuvre  to  be  executed  with  facility.  Vessel  was  moored  at  5.15  p.m. 
The  shore  pipe  was  connected  by  5.29,  dredging  pipe  was  started,  and  all  was  discharged 
by  5.40,  or  in  11  minutes.  Vessel  then  returned  to  Brunsbuttell,  where  she  arrived  at 
6.23  p.m.  The  whole  operation  of  dredging,  transporting  for  12  kilometres,  etc.,  dis¬ 
charging  and  returning,  occupying  2  hours  40  minutes. 


B1 


We  were  permitted  to  attend  and  witness  the  above  operations  by  the  kindness 
and  courtesy  of  Herr  Gilbert,  Chief  Engineer  Inspector  of  the  Brunsbuttel  district. 

The  above  work,  including  delays  for  docking  out  of  Canal,  transporting,  etc., 
deducting  25  per  cent,  for  portion  left  in  bottom  of  holds,  increase  in  bulk,  etc,,  and 
taking  average  of  wages,  stores,  upkeep,  etc.,  from  previous  table,  the  following  table 
gives: — 


Date. 

Total  Time 
Dredging, 
Transporting, 
&c. 

Total  Quantity 
after 

deducting 

25  per  cent. 

Total  Cost  of 
Wages 
and  Upkeep. 

Cost  per 
Cubic 
Metre. 

Equivalent 
in  U.  S.  A. 
currency  per 
Cubic  Metre. 

Equivalent 
in  U.  S.  A. 
currency  per 
Cubic  Yard. 

Hrs.  Mins. 

Cubic  Metres. 

Marks. 

Pfennig. 

Cents. 

Cents. 

900 

64.63 

Sept.  30th,  1902 

4  40 

Cubic  Yards. 

Dollars. 

7.18 

1.666 

1.040 

1,177.2 

15.79 

The  above  results,  especially  that  of  the  long  period  extending  from  October  14th, 
1901,  to  August  1st,  1902,  where  on  the  average  a  cubic  metre  of  solid  material  is  dredged 
for  7.1  pfennigs  (.986  cent)  the  cubic  metre,  appear  to  us  to  be  very  good. 

The  Fruhling  system  is  intended  to  advance  and  cheapen  the  process  of  dredging 
by  making  it  possible  to  apply  the  suction  system  to  soils  that  have  hitherto  not  been 
available  for  such  a  system,  with  its  consequent  economy. 

Until  about  thirty  years  ago  dredging  was  accomplished  by  buckets  upon  the  well- 
known  method,  but  after  the  cutting  of  the  Suez  Canal  through  sand  by  means  of  the 
Bazine  or  suction  system  of  dredging,  it  was  recognized  that,  in  the  case  of  sandy  soils, 
a  centrifugal  pump,  acting  upon  a  suction  pipe  whose  nozzle  was  placed  close  to  the  sub¬ 
merged  sand  it  was  desired  to  dredge,  would  clear  away  such  spoil  more  quickly  and 
more  economically  than  the  bucket  system  of  dredging,  and  this  centrifugal  pump  suction 
system  has  been  applied  ever  since  with  economy  and  advantage  wherever  the  soil  has 
been  sufficiently  sandy.  For  clay  or  heavy  soils,  however,  the  suction  system  has  never 
yet  been  satisfactory,  and  bucket  dredging  has  consequently  continued  for  situations  in 
which  such  soils  are  met.  Herr  Fruhling’s  invention  has  for  its  object  the  application 
of  suction  dredging  to  soils  that  are  less  sandy  and  more  in  the  nature  of  mud  or  clay 
than  has  hitherto  been  possible  for  under  any  previously  known  suction  system. 

The  system  may  be  briefly  described  as  a  combination  of  mechanism  in  which 
mechanical  attrition  is  applied  to  heavy  soil,  and  the  same  is  simultaneously  moistened 
by  water  projected  upon  it,  so  as  to  reduce  the  soil  by  mixture  with  water  to  mud,  or 
an  emulsion  of  sufficient  fluidity  to  be  acted  upon  by  the  suction  of  a  centrifugal  pump, 
thus  enabling  heavy  soils  to  be  worked  with  the  same  facility  as  sand.  The  soil  in  the 
neighborhood  above  referred  to  appears  to  have  been  easily  dealt  with  in  this  way,  and 


32 


it  would,  we  think,  be  desirable  if  a  sample  of  the  material  in  its  atomized  and  undiluted 
state  be  obtained  for  comparison  with  any  soil  that  it  is  proposed  to  deal  with  under 
this  system.  There  appears  to  be  no  doubt  that  many  soils,  hitherto  capable  of  being 
worked  only  by  the  bucket  or  grab  system,  can  under  the  Fruhling  system  be  econom¬ 
ically  treated  by  suction,  and  therefore  we  regard  the  demonstration  as  most  successful, 
proving  a  great  advance  in  economy  and  despatch  in  future  dredging  operations. 

Two  patents  have  been  submitted  to  us,  namely,  19239  of  1898  and  16797  of  1900, 
the  first  being  for  the  method  of  mixing  the  spoil  with  sludge,  and  removing  it  upon 
the  suction  system  as  above  described,  and  the  second  being  for  a  skilful  method  of 
mixing  the  sludge  with  water  while  it  is  deposited  in  the  interior  of  the  hopper  for 
the  purpose  of  being  carried  away  to  the  dumping-ground,  and  in  such  manner  as  to 
keep  the  spoil  sufficiently  mixed  with  liquid  to  be  pumped  out  of  the  hopper  and  de¬ 
posited  through  the  pipes  on  shore.  In  this  way  a  vessel  similar  to  the  Nicolaus,  con¬ 
structed  under  the  two  patents  above  referred  to,  is  adaptable  both  for  winning  spoil 
from  docks,  harbors  and  such  like  places,  when  the  soil  is  less  sandy  than  has  hitherto 
been  possible  for  suction,  and  is  also  adaptable  to  carry  such  spoil  to  a  distance,  and 
deliver  it  through  pipes  to  the  required  place  for  making  up  artificial  land,  as  is 
frequently  required  in  harbor  construction. 


We  are,  Dear  Sir, 

Yours  faithfully, 


(Signed) 


FLANNERY,  BAGGALLAY  &  JOHNSON. 


33 


Report  No.  2. 

IReport 

ON  THE 

FRtfHLING  SYSTEM  OF  DREDOmO 

MADE  TO 

THE  INTERNATIONAL  NAVIGATION  CONGRESS,  DUSSELDORF,  1902. 

BY 

SCHOLER, 

Kais.  Regierungsrath  and  Member  of  the  Imperial  Canal  Commission  at  Kiel. 


The  dredging  operations,  which  are  necessary  to  maintain  the  Emperor 
William  Canal,  have,  owing  to  the  special  conditions  under  which  they  are  to 
be  carried  on,  necessitated  the  adoption  of  a  new,  specific  method  of  dredging 
by  suction,  and  to  make  extensive  trials  in  this  respect;  and  as  very  satisfac¬ 
tory  results  have  been  obtained  during  these  trials,  the  dredger  Nicolaus  has 
been  constructed  on  the  principle  adopted,  and  thus  the  new  method  has 
been  thereby  inaugurated  for  the  first  time. 

The  peculiar  constructions  in  connection  with  the  new  method  are  the 
invention  of  Regierungs-Baumeister  0.  Friihling  in  Brunswick,  and  their 
details  as  well  as  the  conditions  which  have  led  to  its  adoption  and  the  trials 
made  therewith  are  described  in  the  present  paper,  because  the  results  obtained 
during  the  trials  seem  to  point  to  the  possibility  that  dredgers  of  similar  con¬ 
struction  may  be  adopted  elsewhere,  too,  with  advantage. 

The  chief  duties  which  the  new  dredger  constructed  for  the  Emperor 
William  Canal  will  have  to  perform,  and  which  were  specially  kept  in  view  in 
working  out  all  its  details,  were  to  keep  open  the  entrance  of  the  canal  into 
the  River  Elbe,  for  which  purpose  it  will  have  to  clear  away  large  quantities 
of  mud,  which  the  river  is  continually  depositing  in  that  locality;  and  also  to 
carry  out  small,  odd  jobs  of  dredging  in  the  canal  itself,  and  in  addition  thereto 
to  widen  the  bed  of  the  canal  at  passing  places  and  lay-by  berths. 

Besides  these  chief  duties,  the  new  dredger  was  also  to  serve  as  a  break¬ 
down  floating  derrick  in  case  of  accidents,  to  remove  wrecks  and  to  clear  away 
with  expedition  any  accumulation  of  sand  caused  by  such  break-downs  or 
wrecks  in  the  canal. 

Ordinary  bucket  dredgers  would  not  have  been  suitable  for  this  purpose, 
especially  for  performing  the  main  duty,  because  their  anchor  chains  and 
attendant  scows  would  have  most  inconveniently  blocked  the  entrance;  besides 
which,  they  would  not  have  possessed  sufficient  mobility  to  make  way  quickly 
for  the  crowded  traffic  continually  passing  through  the  entrance.  Moreover, 
they  would  have  had  to  be  made  of  such  large  dimensions,  to  be  able  to  fully 


Inventor. 


Use  of 
dredger  for 
maintenance 
and  excavation 
work. 


Use  of 
dredger  for 
salvage  work. 


Advantage 
over  ordinary 
bucket 
dredger. 


34 


Advantage  for 
ordinary  suc¬ 
tion  dredger. 


Reduction  of 
water  lifted 
with  dredged 
material,  &c. 


Description  of 
Invention. 


cope  with  the  work,  that  the  cross-section  of  the  canal  would  have  been  unable 
to  accommodate  them. 

Suction  dredgers  of  the  ordinary  construction  would  have  been  equally 
unsuitable  for  the  chosen  purpose,  because  the  material  to  be  lifted  mainly 
consisted  of  soft  mud  or  silt,  which  could  not  have  been  worked  with  such 
dredgers,  because  it  could  not  have  been  separated  with  sufficient  rapidity  from 
the  excessively  large  volumes  of  water  which  have  to  be  dealt  with  in  this 
particular  instance. 

On  the  other  band,  there  were  several  good  points  to  recommend  the 
new  dredger  invented  by  Eegierungs-Baumeister  Friihling,  who  had  carried 
out  with  it  experiments  on  several  occasions,  and  also  small  odd  jobs  near 
Rendsburg  in  the  vicinity  of  the  canal,  with  remarkably  good  results. 

This  invention  is  an  improvement  on  the  ordinary  suction  dredger,  and 
its  advantages  mainly  consist  in  the  feature,  that  the  volume  of  water  lifted 
with  the  dredged  material  can  be  regulated  at  will,  and  limited  to  the  mini¬ 
mum  quantity,  which  renders  dredgers  of  this  description  specially  suitable 
for  removing  soft  mud.  Moreover,  it  is  possible  to  work  with  these  dredgers 
to  a  uniformly  level  bottom,  and  the  formation  of  holes  and  deep  pools  usually 
left  by  ordinary  suction  dredgers  is  thereby  avoided;  for  this  reason  ordinary 
suction  dredgers  cannot  be  used  in  canals  where  the  finished  excavation  is  not 
to  exceed  a  certain  fixed  maximum  cross-section. 

The  special  apparatus  by  which  the  advantages  mentioned  above  are 
attained  consists  of  a  dredging  end-piece  or  head  of  special  construction  which 
is  fixed  to  the  end  of  the  suction  tube,  and  is  formed  by  two  principal  parts. 

One  of  these,  the  foremost  portion,  is  of  the  shape  of  dredging  bucket 
which  excavates  the  ground  mechanically,  leaving  a  level  flat  bottom. 

The  othei’,  hindmost  portion  forms  a  chamber  or  receiver,  closed  all 
round,  into  which  the  excavated  material  is  pushed  in,  and  into  which  the 
necessary  volume  of  water  can  also  be  admitted  in  adjustable  proportions. 
The  excavated  material  and  requisite  quantity  of  water  for  pumping  it  away 
are  then  mixed  in  the  receiver,  and  the  slurry  thus  formed  is  lifted  by  the 
pump. 


Trials  with  a 

remodelled 

lighter. 


The  receptacle  wherein  the  excavated  material  is  mixed  with  water  is 
suitably  constructed  for  that  purpose,  and  when  working  in  compact  ground 
the  work  of  excavation  and  mixing  is  assisted  by  pressure  water,  which  can 
be  directed  in  powerful  streams  upon  the  exact  spot  where  the  ground  is  to  be 
excavated.  This  system  of  dredging  seemed  to  be  eminently  adapted  to  the 
existing  requirements,  and  it  was,  therefore,  proposed  for  adoption,  on  the 
understanding,  however,  that  its  efficiency  was  to  be  first  proved  by  pre¬ 
liminary  trials  on  a  larger  scale. 

To  carry  out  these  experiments  an  existing  steam  lighter  was  recon¬ 
structed  and  fitted  up  as  a  dredger  by  Friihling  on  the  system  invented  by 
him,  secured  by  patents. 

The  lighter  was  of  the  usual  construction,  had  stowage  room  of  150 


35 


cubic  meters  capacity,  was  fitted  with  a  compound  engine,  with  surface 
condensation,  of  185  indicated  H.P.,  a  boiler  with  65  square  meters  heating 
surface  working  at  8  atmospheres  excess  pressure,  2  hopper- winches,  and  a 
simple  anchor  winch  worked  by  hand  gear. 

To  turn  her  into  a  dredger,  the  additional  fittings  consisted  of  a  suction 
pump  with  direct  acting  engine,  suction  and  delivery  pipes  for  dredging,  pipes 
for  water  for  mixing  purposes,  pump  and  piping  for  forcing  pressure  water,  a 
dredging  head,  a  dredging  crane  combined  with  two  stern  winches,  and  a 
double  forward  winch. 

The  dredging  pump  was  a  centrifugal  pump  with  impeller  900  milli¬ 
meters  in  diameter,  and  made  200  revolutions  per  minute.  It  was  driven  by 
a  direct  coupled  engine  of  75  I.H.P. 

The  dredging  conduit  consisted  of  a  plate  girder  with  two  fixed  arms. 
The  two  arras  enclosed  the  hull  between  them,  reaching  up  on  either  side,  and 
turned  round  pivots  fixed  to  the  sides  of  the  hull.  The  other  end  of  the  girder 
was  suspended  by  wire  ropes,  working  round  pulleys,  from  the  dredger  crane 
which  was  fixed  on  the  deck  abaft.  The  dredging  head,  of  special  construc¬ 
tion,  was  fixed  underneath  the  lower  end  of  the  ladder,  and  two  pipes  led 
from  it  on  to  the  deck.  The  suction  pipe  was  fixed  on  the  port  side,  and  ran 
up  on  one  arm  to  the  pump.  The  other  arm,  on  the  starboard  side,  carried 
two  more  pipes,  one  for  conveying  the  pressure  water  to  the  dredging  head, 
the  other  the  water  necessary  for  mixing  the  slurry  in  the  receiver.  The 
pressure  water,  as  already  stated,  was  supplied  by  a  special  force  pump.  The 
other  pipe,  conveying  water  to  the  receiver  for  mixing  with  the  dredgings, 
had  an  inlet  close  to  the  end  of  the  arm,  the  size  of  the  opening  of  which  could 
be  opened  and  closed  and  regulated  by  a  valve  from  the  deck,  and  more  or  less 
water  admitted  to  the  pipe  at  will.  The  water  to  be  conveyed  to  the  mixer 
and  receiver  was  sucked  in  by  the  sucking  action  of  the  dredging  pump. 

The  dredging  head  was  3.5  meters  broad.  When  about  to  dredge,  it 
was  lowered  by  the  crane  into  position,  and  was  dragged  along  the  bottom  by 
the  dredger. 

The  dredger  was  moved  ahead  by  two  powerful  forward  winches,  and 
made  a  straight  cut  3.6  meters  broad;  arrived  at  the  end  of  the  cut,  it  was 
hauled  back  by  the  two  stern  winches,  and  moving  forward  again  made  a 
second,  deeper  cut  or  changed  its  position  and  made  a  fresh  cut  sideways. 

The  excavated  material  was  delivered  by  the  pump  into  barges  lying 
alongside,  or  was  forced  through  a  delivery  pipe  line,  100  meters  long,  and 
deposited  at  convenient  places  on  the  banks. 

The  dredger  started  work  in  the  autumn  of  1900,  and  was  subjected  to 
extensive  trials.  After  it  had  undergone  various  improvements  and  its  crew 
had  been  properly  trained  to  the  work,  the  dredger  worked  with  perfect  satis¬ 
faction  both  in  mud  and  in  sand,  and  is  still  continuously  employed  in  main¬ 
tenance  work  on  the  canal. 

The  work  performed  by  the  dredger,  considering  the  small  power  of  the 


36 


pump,  is  truly  remarkable.  It  can  load  a  scow  of  150  cubic  meters  capacity 
in  15  minutes.  Working  in  mud,  the  dredger  delivers  the  excavated  material 
in  such  a  state  of  consistency  that,  if  caught  up  in  a  tub  at  the  mouth  of  the 
delivery  pipe,  it  forms  a  heap  that  will  stand  for  hours  without  running  off. 
According  to  the  density  of  the  mud,  when  deposited,  it  contains  from  60  to 
90  per  cent,  of  excavated  solid  material  in  its  mass. 

When  excavating  fine  sand  the  work  of  the  dredger  also  compares 
favorably  with  that  performed  by  other  suction  dredgers,  though  the  work 
done  in  this  case  did  not  give  such  good  results  as  when  excavating  mud. 
When  dealing  with  fine  sand,  the  volume  of  slurry  delivered  by  the  dredger 
only  contained  about  20  per  cent,  of  excavated  material  in  its  mass. 

After  lengthy  trials  and  numerous  alterations  in  the  shape  of  the 
excavating  head,  the  dredger  now  works  as  satisfactorily  in  sand  as  in  mud. 
The  quantity  of  sand  delivered  in  the  slurry  can  now  be  increased  in  propor¬ 
tion  to  the  power  of  the  pump,  and  from  40  to  50  per  cent,  of  it  can  be  attained 
without  difficulty. 

H  view  of  the  satisfactory  results  attained  during  the  trial  working, 

&ClOJ)v0Cl  ctuCl 

Mcoiawa  built  Fruhling’s  system  of  dredging  has  been  definitely  adopted  for  the  newly  pro¬ 
jected  dredger  Nicolmis,  which  has  been  designed  in  accordance  with  the 
special  requirements  of  the  Emperor  William  Canal  already  mentioned,  and 
the  experience  gained  during  the  experiments  has  been  duly  utilized  in  work¬ 
ing  out  its  details. 

The  design,  construction  and  delivery,  fully  equipped  for  the  work,  was 
entrusted  to  Eegierungs-Baumeister  Friihling,  of  Brunswick.  The  dredger 
was  built  in  the  course  of  1900  and  1901,  delivered  in  September  1901  and  set 
to  work, 

Description  of  The  equipment  for  dredging  has  been  arranged  in  a  manner  similar  to 

that  adopted  on  the  experimental  dredger,  with  the  exception  that  the  arms 
of  the  ladder  and  the  various  pipes  have  been  combined  into  one  whole,  and 
are  carried  up  through  a  gap  in  the  centre  instead  of  at  the  sides  of  the  hull. 
The  object  of  this  alteration  was  to  provide  better  protection  for  the  various 
conduits,  to  give  the  dredger  more  mobility,  and  to  enable  other  barges, 
scows  and  boats  to  lie  alongside  more  conveniently. 

The  dredging  conduit  is  formed  by  a  box  girder,  of  quadrangular  cross- 
section,  which  has  an  enlargement  at  its  lower  end,  and  rests  on  a  horizontal 
shaft  at  its  upper  end.  The  dredging  head  is  fixed  to  the  enlargement  at  the 
lower  end,  and  the  box  girder  rests,  by  means  of  the  shaft  at  its  upper  end,  in 
the  central  gap  on  plummer  blocks. 

The  construction  of  the  dredging  head  is  similar  to  that  on  the  experi¬ 
mental  dredger. 

The  suction  pipe  is  led  on  the  port  side  of  the  dredging  head,  through 
the  enlargement,  up  through  the  inside  of  the  box  girder.  It  consists  of  a  400- 
millimeter  tube  which  ends  in  the  horizontal  shaft  on  the  box  girder  in  a 


37 


cylinder  which  surrounds  a  similarly  shaped  junction  pipe,  leading  to  the 
suction  pump. 

The  water  intended  for  mixing  with  the  excavated  material  is  led 
down  through  the  inside  space  left  unoccupied  by  the  suction  pipe.  For  this 
purpose  the  upper  end  of  the  box  girder  is  closed  by  a  diaphragm,  and  inlet 
holes  are  provided  in  the  sides  of  the  girder  for  the  admission  of  water. 
These  inlet  holes  can  be  opened  and  closed  at  will  by  movable  louvres  worked 
from  the  deck. 

The  piping  for  conveying  pressure  water  to  the  mixing  chamber  is  car¬ 
ried  on  the  top  plate  of  the  box  girder  and  is  connected  with  the  force  pump 
by  movable  pipes.  The  piping  consists  of  three  pipes  laid  side  by  side  and 
leading  down  to  the  dredging  head,  where  they  branch  off  into  a  number  of 
single  pipes,  some  of  which  lead  to  the  cutting  edge  of  the  head,  others  to  the 
interior,  where  they  can  assist  the  cutting  apparatus  at  will  in  loosening  the 
ground  with  pressure  water  when  working  in  stiff  soil. 

The  force  pump  delivering  pressure  water  is  a  direct  acting  Blake  pump 
of  40  H.P. 

The  dredging  pump  has  an  impeller  of  1,150  millimeters  diameter,  is 
driven  direct  by  a  compound  engine  of  150  H.P.,  and  makes  from  200  to  250 
revolutions  per  minute.  The  pump  delivers  the  excavated  material  through  a 
force  pipe  laid  along  the  deck  into  the  hold  of  the  dredger,  or  through  lateral 
overflow  pipes  into  scows  moored  alongside  the  dredger,  or  through  an  exten¬ 
sion  of  the  delivery  pipe  to  a  distance  of  200  meters,  and  up  to  a  height  of  5 
meters  on  the  banks  of  the  canal  sideways. 

The  whole  dredging  conduit  is  suspended  from  a  powerful  crane  fixed 
abaft  on  the  deck.  This  crane  can  lift  20  tons  at  a  speed  of  3  meters  per  min¬ 
ute,  and  forms  at  the  same  time  a  stiff  connection  between  the  two  stern 
halves  of  the  hull  of  the  dredger.  The  dredging  conduit  resting  in  the  central 
gap  is  removable,  and  the  whole  conduit  can  be  lifted  out  of  the  gap  and 
hoisted  above  deck.  When  at  work  the  dredger  is  generally  propelled  by 
screws,  without  any  chains.  For  this  purpose  there  are,  besides  the  engines 
working  the  pumps,  two  special  engines,  of  120  H.  P.  each,  provided  for  work¬ 
ing  the  propellers.  These  can  propel  the  dredger  at  a  speed  of  16  kilometers 
per  hour  unloaded,  and  at  12  kilometers  when  loaded.  When  excavating 
ground  of  medium  stiffness,  the  dredger  can  travel  forward  at  a  sufficient 
speed  to  enable  the  dredging  head  to  cut  just  sufficient  material;  that  is,  the 
dredging  head  will  excavate  as  much  material  in  front  as  the  pump  will  be 
able  to  remove  from  the  mixing  chamber  behind. 

The  dredging  of  the  bottom  is  done  in  this  case  also  in  long  strips,  3.5 
meters  wide.  After  leaving  off  work  and  returning  from  the  dumping  ground, 
or  when  starting  work  on  a  new  site,  the  dredger  can  take  up  its  position  with¬ 
out  difficulty  with  the  help  of  convenient  land  marks.  Being  able  to  move 
the  dredger  forward,  when  at  work,  by  means  of  propellers  only,  and  without 
any  chains,  has  its  special  advantages,  when  working  near  the  entrance  of  the 


38 


canal,  as  it  does  not  interfere  with  navigation,  and  removes  all  dangers  arising 
from  the  use  of  chains  in  dredger  working.  This  arrangement  has,  besides, 
the  advantage  of  increasing  the  quantity  of  work  done  by  the  dredger,  because 
a  great  deal  of  time  is  usually  lost  in  dropping  and  picking  up  the  chains, 
when  working  with  other  kinds  of  dredgers,  which  time  can  be  saved  com¬ 
pletely  now  and  more  profitably  employed  in  doing  useful  work. 

The  dredger  is  provided  with  compartments  for  loading  the  excavated 
material;  it  is  constructed  as  a  hopper  dredger.  It  was  advisable  to  adopt  this 
construction  in  view  of  the  special  conditions  obtaining  at  Brunsbiittel  (at  the 
canal  entrance),  which  necessitated  the  adoption  of  some  method  of  dredging 
that  was  to  be  as  simple  as  possible,  and  could  be  effected  by  employing  a 
single  boat  only.  All  three  compartments  together  will  hold  400  cubic  meters; 
there  being  two  of  100  cubic  meters  each,  and  one  of  200  cubic  meters  capacity. 
The  two  smaller  holds  are  one  on  either  side  of  the  central  gap  or  slit,  and  the 
large  one  in  front  of  the  engine  room  and  stokehold,  which  are  placed  amid¬ 
ships. 

Such  a  distribution  of  the  holds  makes  it  possible  to  properly  adjust  the 
loading  of  the  boat  and  to  distribute  the  material  uniformly,  so  that  the 
dredger,  whether  loaded  or  empty,  will  always  float  on  an  even  keel. 

The  dredger  is  emptied  through  hoppers  in  the  bottom,  which  are  opened 
and  closed  by  four  steam  winches  placed  on  deck. 

There  is  besides  a  contrivance  by  which  the  material  in  the  holds  can  be 
lifted  by  the  suction  pump  and  delivered  on  to  the  banks.  The  dredger  is  fitted 
also  with  an  elevator  apparatus. 

These  equipments  also  were  found  necessary  to  suit  the  working  to  the 
special  conditions  on  the  Emperor  William  Canal,  as  there  are  very  few  places 
along  its  route  where  the  hoppers  can  discharge  the  excavated  material,  and 
special  provisions  had  to  be  made,  therefore,  to  be  able  to  deposit  the  dredgings 
at  convenient  places  anywhere  on  the  banks  direct  from  the  dredger. 

The  elevator  equipment  provided  for  this  purpose  consists  of  three  pipe 
conduits  built  into  the  hull  and  leading  to  the  suction  pump.  The  pipes  run 
alongside  the  holds  and  have  a  number  of  openings  closed  by  flaps,  leading  to 
the  holds.  The  dredgings  in  the  holds  can  be  exhausted  through  these 
openings,  which  being  distributed  all  over  the  bottoms  of  the  holds  render  it 
possible  to  empty  the  three  compartments  gradually  and  uniformly  all  over 
their  areas.  In  case  of  the  dredgings  in  the  holds  having  become  solidifled 
they  can  be  remixed  with  water  before  the  material  is  lifted  by  the  suction 
pump,  for  which  purpose  there  are  four  other  tubes  provided  besides  the  three 
suction  pipes  already  mentioned.  The  four  pipes  for  the  delivery  of  the  water 
required  for  mixing  have  also  openings  into  the  holds,  which  are  placed 
opposite  the  inlets  to  the  suction  pipes. 

The  sucking  action  of  the  pump  produces  a  stream  running  across  the 
hold  from  the  delivery  to  the  suction  pipes,  which  loosens  the  deposited 
material  in  the  hold  and  carries  it  away  with  it.  The  loosening  can  be 


39 


assisted  by  pressure  water,  which  can  be  conveyed  down  special  tubes  into  the 
waterpipes  and  intensifies  the  streams  of  water  across  the  holds. 

This  arrangement  which  is  also  the  invention  of  Regierungs-Baumeister 
Friihling,  and  has  been  patented,  has  also  answered  very  well. 

The  hull  of  the  dredger  is  46.68  meters  long  by  8.48  meters  beam,  and 
3.7  meters  deep.  These  dimensions  have  been  adopted  to  suit  the  cross-section 
of  the  canal,  so  that  the  dredger  can  easily  turn  round  and  manoeuvre  about 
on  the  canal.  In  view  of  these  requirements,  the  dimensions  given  above  could 
not  very  well  be  exceeded. 

Over  and  above  the  machinery  and  equipment  already  mentioned,  there 
are  also  on  board  a  central  condensing  apparatus  with  forewarmer,  an  electric 
light  installation  for  arc  and  glow  lamps  and  projectors,  a  steam  steering  gear 
and  the  usual  auxiliary  machinery. 

There  is  besides  on  deck  a  powerful  double  forward  winch,  which  can 
jnoyejbhe  dredger  forward  at  a  speed  of  10  meters  per  minute  and  exert  a  pull 
of  16  tons.  This  is  provided  for  the  purpose  of  hauling  the  dredger  forward, 
when  it  is  intended  to  work  with  chains  and  without  propellers.  Steam  is 
supplied  by  2  tubular  boilers  working  at  a  pressure  of  8  atmospheres  above 
atmospheric  pressure,  and  having  a  heating  surface  of  110  square  meters  each. 

The  consumption  of  coals  is  0.35  ton  per  hour  while  dredging,  and  0.24  ton 
when  steaming  with  full  load. 

In  order  to  enable  the  dredger  to  fulfil  its  subsidiary  duties  as  a  break- use  as  break¬ 
down  floating  derrick  and  salvage  boat,  it  is  fitted  in  a  convenient  manner  deS:k°and^ 
with  all  the  necessary  equipment  for  such  purposes,  as,  e.  g.,  with  ample 
pumping  power,  etc.  The  powerful  crane  can  be  used  in  case  of  break-downs 
and  for  raising  wreckage;  and,  as  already  stated,  there  is  also  the  possibility  of 
self-filling  and  self-clearing  the  holds  in  the  boat. 

The  crew  consists  of  the  captain,  cockswain,  3  sailors,  cook,  2  engineers 
and  3  stokers;  11  men  in  all. 

The  efficiency  of  the  work  done  by  the  dredger  as  regards  consistency  work 
of  the  excavated  material  and  proportion  of  solid  matter  contained  in 
dredgings  is  the  same  as  that  of  the  experimental  dredger.  Owing  to  the  use 
of  a  more  powerful  pump,  the  quantity  of  work  done  by  the  new  dredger  is,  of 
course,  greater.  When  working  at  the  canal  entrance  near  Brunsbiittel,  the 
holds  of  400  cubic  meters  capacity  are  upon  an  average  filled  in  16  minutes. 

The  excavated  material  is  then  taken  away  to  a  distance  of  3  kilometers  and 
discharged  through  the  hoppers.  Working  ten  hours  the  dredger  can  in  this 
manner  make  13  such  full  trips  on  an  average,  including  any  delays  by  navi¬ 
gation.  The  quantity  of  work  done  in  excavation  can  not,  owing  to  local 
conditions,  be  arrived  at  in  any  other  way  than  by  measuring  the  volume  of 
material  deposited  in  the  holds.  Deducting  from  the  cubic  capacity  of  the 
holds  33  per  cent,  on  account  of  incomplete  filling  and  for  increase  in  bulk,  the 
quantity  of  earthwork  removed  by  the  dredger  under  above-mentioned  work¬ 
ing  conditions  may  be  reckoned  in  round  figures  at  1,000  cubic  meters  per 


40 


hour,  and  the  day’s  work  at  ten  working  hours,  consisting  of  excavation, 
carrying  off  the  dredgings  to  a  distance  of  3  kilometers  and  discharging  them 
through  the  hoppers  at  3,500  cubic  meters. 

The  working  expenses  of  the  dredger  amount  tc  150  marks  per  day  upon 
an  average. 

Calculations  have  also  been  made  with  regard  to  the  specific  gravity  of 
tlje,  excavated  material. 

According  to  the  conditions  prevailing  at  Brunsbiittel  it  has  been  found 
that  the  dredger  can  perform  the  greatest  amount  of  work  if  the  specific 
gravity  of  the  dredgings  is  kept  down  to  1.275.  The  principal  bulk  of  the  mud, 
which  has  to  be  dredged  at  Brunsbiittel  to  standard  cross-section,  as  it  lies  at 
the  bottom,  that  is,  before  it  has  time  to  consolidate  completely,  has  an  average 
specific  gravity  of  about  1.3  or  1.33  respectively.  At  greater  depths  this  increases 
to  1.4,  and  even  as  much  as  1.6.  According  to  these  weights,  the  percentage 
of  solid  material  contained  in  dredgings  of  a  specific  gravity  of  1.275  woulfi. 
amount  to  90  per  cent.,  or  83  per  cent.,  or  68  per  cent,  or  46  per  cent, 
respectively. 

Before  the  dredger  Nicolaus  started  work,  the  necessary  dredging  to 
be  done  at  the  canal  entrance  was  performed  by  a  large  bucket  dredger  and 
three  steam  hopper-barges.  Working  under  similar  conditions  as  those  upon 
which  the  work  done  by  the  dredger  Nicolaus  has  been  computed  above, 
the  four  boats  excavated  1,500  cubic  meters  only  per  day,  and  entailed  a  daily 
w'orking  expenditure  of  about  380  marks  in  round  figures. 


(S 


